Breech bolt mechanism



March 29, 394% F, L RATAlCZAK 2,465,749.

BREECH BOLT MEGHANISM Filed Jan. 27, 1945 2 Sheets-Sheet l March 29, i949, F. l. RATAICZAK 2,465,749

BREECH BOLT MECHANISM Filed Jan. 2'@ 1945 2 Sheets-Sheet 2 60 .9o 66 62 5g SZ IN VEN TOR. 'px v v Patented Mar. 29, 1,949

BREECH BOLT MECHANISM Francis I. Rataiczak, Dayton, Ohio, assignor to General Motors Corporation, Dayton, Ohio, a

corporation of Delaware Application `anuary 27, 1945, Serial No. 574,844

8 Claims. l

This invention relates to ordnance and more particularly to an improved re control mechanism for use in the .60 caliber machine gun disclosed in my co-pending application S. N. 536,229, filed May 19, 1944, and now designated by the War Department as the Cal. .60 Tl'lES Machine Gun. I

It is an object of this invention to provide means for synchronizing the ring of the .60 caliber T17E3 machine gun with the operation of an airplane propeller or other moving part.

Another object of this invention is to provide an improved re control mechanism which may be substituted for the corresponding mechanism on the .60 caliber machine guns of the type now in use.

In the .6G caliber Tl'lES machine gun, as disclosed in my co-pending application, the firing pin is carried by the bolt and is moved into firing position by the bolt whenever the bolt moves into its forward position, whereas, in the construction disclosed herein, the firing pin is a spring loaded rng pin controlled by a sear which in turn is controlled by mechanism synchronized with an airplane propeller or the like. It is an object of this invention to mount this sear and the sear trigger within the bolt so as to be movable therewith.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings, wherein a preferred form of the present invention is clearly shown.

In the drawings:

Fig. i of the drawings shows, somewhat diagrammatically, a machine gun of the type in which my improved re control mechanism is used;

Fig. 2 is a top view of the bolt head;

Fig. 3 is a side view of the bolt head showing parts broken away;

Fig. 4 is a plan view of the bolt assembly with parts broken away so as to showthe re control mechanism before the bolt head is rotated into its locked position;

Fig. 5 is a vertical sectional view of the bolt assembly showing the elements in the same relative position as in Fig. 4;

Fig. 6 is a sectional View taken substantially on line 6-6 of Fig. 8 showing the relationship of the parts when the bolt and the bolt head are locked in battery and prior to the time that the the position of the firing pin after it has moved into ring position and while the bolt is still in battery; Y

Fig. 8 is a sectional View taken on line 8 8 of Fig. 7; and

Fig. 9 is a sectional view taken in the plane of the sear trigger 92 and is partly diagrammatic, showing the relationship of the synchronizing mechanism to the firing pin sear trigger.

Fig. 1 of the drawings diagrammatically shows a gun in which all of the parts except for the bolt assembly and re control mechanism are identical in construction and operation to the corresponding parts shown in said (zo-pending application to which reference may be made, if necessary, for a more detailed description of the main gun construction. The most essential parts of the gun are the receiver or breech housing l0, the barrel 20, the breech ring 22, the shell feeding mechanism 24, the bolt buiier 26, the bolt body 30, and the bolt head 32, all of which operate in a manner now well known to those skilled in the art and need no further description except insofar as necessary for an understanding of the operation of thev re control mechanism set forth herein.

The bolt body 30 is mounted in the receiver I0 in accordance with well known practice and is adapted to reciprocate back and forth within the receiver l0 during operation of the gun. As

Ashown in Fig. 4, the bolt body comprises a relatively long, narrow member having a central aperture in which the shank 38 of the bolt head 32 is journaled. The bolt head 32 comprises a rearwardly extending hollow shaft or shank 38 within which a portion of the lire control mechanism is mounted. The forward end of the bolt head is provided with a pair of rollers 42 arranged as shown for cooperation with the cam surfaces 44 provided on the forward end of the bolt body 30 so as to cause relative rotation between the bolt head 32 and the bolt body 30 when the bolt body and bolt head move into battery position. The rollers 42 also cooperate with cam surfaces 56 provided on the breech ring 22 which assist to rotate the bolt head relative to the bolt body 30 and relative to the breech ring 22. This rotation of the bolt head causes it to be held in battery position by means of the complementary interrupted screw type lugs 48 and 50 provided on the bolt head and the breech ring respectively. The interlocking lugs 48 and 50 are of the well known interrupted screw type of lugs. Upon recoil of the barrel 20 together with the breech ring 22, the rollers 42 are moved rearwardly to engage cam surfaces 54 on the receiver so as to rotate the bolt head relative to the breech ring 22 and the bolt body 30 thereby disengaging the interrupted screw type lugs 48 and 50 so as to allow the bolt head to move back with the bolt body throughout the remainder of the movement of the bolt body. As the cam surfaces 54 rotate the bolt head 32 the rollers 42 also cooperate with the cam surfaces. on theebolt body 30 so as to provide relative rotation between the bolt head 32 and the bolt body 30 to cause partial separa.- tion of the bolt head 32 and the bolt body 30 through the riding of the lugs 60 in helical slotsf in the bolt head cam 62.

The shank 38 of the boltI head 32 is provided with oppositely disposed lugs 60 which serve the same purpose as the corresponding lugs in the gun described in said co-pending application. The shank 30 is slidably supported within the bolt head cam 62 whichr is a sleeve-like member which moves with the bolt body 30 at all times. The lugs 60 engageV helical cam slots within the bolt head' cam 62 so that relative rotation of the bolt head 32 and the bolt body 30 from the position shown in Figs. 4 and 5 to the position shown in Fig. 6 accompanies the sliding movement of the bolt head 32 toward the bolt body 30. Opposite relative rotation accompanies the slidingA movement ofthe bolt head 32 away from the bolt body.. The construction and operation of the lugs 60 and the bolt headcam 62' need' no further description as the specio constructionof these elements forms, no part of this invention. Since the cooperation between. the rollers.l 42 and the cam surfaces 44, 46 and` 54 is essentiallyv the same as in thegun set forth insaid'. co-pending applicationv they likewise need no further description.

Referring now to the` disclosure, in Figs. 4 through 8, the firing pin. 64- is; slidably mounted withinthebolt headas shown.v A spring 66 whichy surrounds the end oi the shank 38 acts through.

the ring pinspring. washer 68 and firing pin spring pin 1.0; to bias,` the ring pin forwardwithin the boltl head.v Thering pin spring pin 10' projectsA through the slots 'I2 and 14 (see Figs- 2' and- 3) provided in the wall of the bolt head shank 38. The -ring; pinspring washerf 68, is: slidably` mounted on thefexterior of. the shank 38 as shown. The.v

rearendi of. the spring 6 6 is arranged in engagement with the firing pin springcollar 7:6 which. is threaded onto-the*l shankv 3.8 so as tofslide with. the shank 38 within the central aperture 80i of the bolt body 30. A notch 82a is provided onJ thez rear end or the firing pin vfor engagement with: theflring'pinsear 84; Theeri'ng pinsears 84. isz pivotally supported; on the ring. pinsear pivotl pin 86 carriedbythe. shank.3.0?.. 'I-heaforward end of' the-'firing pin sear hooks.theflring. pin. 64I at 8'2 as shown. A compression. spring- 901whi'ch is held in'- compression. between theA collar '[61 andf the sear 84 normally holdsthe sear`84 iny engagement withl the firing pin 644 Itshould benoted that thef'bolt` bodyy 30 has been shown. inz a1 tilted position in Figs; 6, 'Zand 8 rather thanishowing the bolt headi and trigger operatingv mechanism in the'A tilted position.

A ring` pin sear triggery 921v which is pivotallyy mounted on a pin` 9'4 carri-ed byf the main bolt bodyv 30' is arranged for engagement with the` rear end of the'vring pin'sear 84 so as to release the sear from the firing; pin byovercoming the force of the springr 90. Pf spring 96'- (see Fig. 8) normally holds thefringpinx sear triggerV out of ring position. For purposes of illustration. I

trigger 92.

have shown the ring pin sear trigger operated by a synchronizing mechanism designated by the reference character 99. The ring pin sear trigger is located so as to be directly in line with the firing pin sear trigger operating member |00 when the bolt body 30 is in its forward or battery position. The member |00 in turn is operated by the reciprocating. cam. member. |.02 connected to the cable |04 which in turn is connected to some moving element which operates in synchronism with the propeller. A spring |06 biases the member |00 out of engagement with the ring pin sear The cable |04 is arranged to pass over a. pulley |08 which may be secured to the side of the gun by any suitable means (not shown) Since thefgun moves longitudinally during recoil, it is essential to arrange the cable and the pulley |=08` theI manner shown so that the pull on the cable resulting from the movement of the gun during recoil will not be enough to cause. the. member |02 to cam the member |00 into gun firing, position.

In referringv to. Figs. 4 through. 7 it is apparent that the firing pin sear 84y reciprocates with the bolt headV relativeto the bolt body during opera,- tion of the gun and that it moves in and out of registry with the ring pin sear trigger 92 each` time. a shell is fired. The rear end. of the ring pin sear is therefore provided. with an inclined cam surface |r|2 whereby the extremev rear end of thev sea-r will` clear the front face of the trigger B2i regardlessof. the; position of the trigger when the sear moves back relative to the trigger. Referring to Fig.,7 of. the drawings., it is apparent that -wlien thev bolt head begins separating from the;

bolt body through the relative rotation. between them during, recoil, the ring pin. spring pin 'i0 carried by the firing-1 pin 64, contacts the rear end ofthe boltvhead canr 6-2" wherebythe firing pin 64 stands; still relative, to the bolt body and moves. with thebolt body rearwardly relativeto the. bolt head; Thus;4 when. the? bolt body moves rearwardly-'relative to the-bolt headpthe spring 66 isI compressed and. the; trigger sear 84: moves into engagementY with the trigger as shown in Fig. 5.

Thereforethe spring.- 66` is'compressedv between the ring 68 andthe collar 16. The ring 68 moves rearwardly with the bolt body 301 relative to the collar llwhich i'sfastened tothe rear end of the shank 32. The firing pin 64movesA rearwardly with the ring 68. The bolt-head' 32 lags behind the bolt body 30 during the recoil producing the relative movement between the 4bolt body and the bolt I head which performs the withdrawal ofthe firing pinandthe-compression oftheispring 66. Upon locking the breech bolt tothe barrel upon thereturnoffthe bolt to battery position, the bolt head together with all of the parts carried thereby move from the relative position in which they are shown in Fig. 5 to the relative position in which they are shown in Fig. 6 in which relative position the Iringpin spring is compressed and thev sear is in registry withthe-trigger 92". Thus, with the parts arranged'- as shown in Fig. 6 (and these parts are arranged in this manner only when the bolt body 7g claims which follow.

What is claimed is as follows:

1. In a rapid fire machine gun having a reciprocating bolt body and a bolt head carried by the bolt body and rotatable relative to the bolt body, a firing pin means movably carried within said bolt head for movement into and out of ring position, means preventing relative rotation between said iiring pin means and said bolt head, a spring urging said firing pin means to move forward into firing position, a sear carried by said bolt head for releasably holding said pin means out of firing position to prevent its forward movement under the impetus of said spring, and trig ger means carried by said bolt body for operating said sear to release said pin means for movement to firing position by said spring.

2. In a rapid re machine gun having a reciprocating bolt body and a bolt head carried by the bolt body and rotatable relative to the bolt body, a ring pin means movably carried within said bolt head for movement into and out of firing position, a spring urging said ring pin means to move forward into ring position, a sear for releasably holding said pin means out of firing position to prevent its forward movement under the impetus of said spring, and trigger means carried by said bolt body for operating said sear to release said pin means for movement to firing position by said spring.

3. In a rapid re machine gun having a reciprocating bolt body and a bolt head carried by the bolt body and rotatable relative to the bolt body, a firing pin means movably carried within said bolt head for movement into and out of firing position, a spring urging said firing pin means to move forward into ring position, a Sear for releasably holding said pin means out of ring position to prevent its forward movement under the impetus of said spring, and trigger means carried by sai-d bolt body for operating said Sear to release said pin means for movement to firing position by said spring, a pivot for said sear carried by said bolt head whereby said scar is pivotally secured to said bolt head so as to move with said bolt head relative to said bolt body.

4. In a rapid fire machine gun having a breech housing, a reciprocating bolt body within said breech housing, and a bolt head carried by said bolt body and rotatable relative to the bolt body, a firing pin means movably carried within said bolt head for movement into and out of firing position, a Sear carreid by said bolt head for releasably holding said pin means out of firing position to prevent its forward movement under the impetus of said spring, sear operating means carried by said bolt body for moving said sear to release said pin means for movement to ring position by said spring, and means carried by said breech housing for engaging said sear operating means.

5. Fire control mechanism for use in a rapid fire machine gun comprising in combination, a reciprocating bolt body, a bolt head rotatablycarried by the bolt body, a ring pin slidably disposed within said bolt head, a sear pivotally secured within said bolt head for engaging said firing pin, and trigger means carried by said bolt body for engaging the sear.

6. In a rapid fire machine gun, a bolt body having a central aperture, a bolt head, said bolt head having a rearwardly extending hollow shaft journalled in said aperture for reciprocation and rotation relative to said bolt body, a iiring pin slidably supported within said bolt head, a sear for releasably holding said firing pin out of ring position, means for supporting said sear within said hollow shaft, means carried by said bolt body for operating said Sear, and means for biasing said nring pin into ring position including spring means within said aperture and surrounding said hollow shaft.

7. In a rapid fire machine gun, a bolt body having a bearing aperture, a bolt head, said bolt head having a rearwardly extending hollow shaft journalled in said bearing aperture, a ring pin slidably mounted within said hollow shaft, a compression spring disposed within said bearing aperture and surrounding said hollow shaft, means connecting said spring and said ring pin so as to bias said firing pin forwardly into ring position, and sear means disposed within said hollow shaft for releasably holding said iiring pin out of firing position.

8. In a rapid re machine gun, the combination, a breech housing, a reciprocating bolt body disposed within said housing, a bolt head rotatably mounted for reciprocation relative to the bolt body, a ring pin slidably mounted within said bolt head, a spring urging said ring pin towards iiring position, a sear for holding said pin out of firing position, sear operating trigger means carried by said bolt body, means carried by said breech housing for actuating said trigger means, said last named means comprising a first reciprocating member for engaging said sear operating means and a second reciprocating member arranged at right angles to said irst reciprocating member and having a cam surface for actuating said first reciprocating member, cable means having one end secured to said second reciprocating member, and pulley means for said cable carried by said breech housing, said cable means having said one end arranged parallel to said housing and having an operating portion passing over said pulley and extending substantially at right angles to said housing.

FRANCIS I. RATAICZAK.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 783,123 Mauser Feb. 21, 1905 1,109,910 Eastwick Sept. 8, 1914 1,454,039 Chevallier May 8, 1923 1,498,542 Gorton June 24, 1924 1,629,651 Browning May 24, 1927 

